The ghost of Walker Bay

Writer: Dr Anina Lee

Strollers on Grotto Beach in Hermanus have no doubt come across ‘mermaids' purses’ washed up on the sand. They are actually shark egg cases from which the little sharks have (usually) emerged.

Does that mean that sharks lay eggs like birds? Well, some of them do 'shed' eggs. About a quarter of all shark species shed eggs into the sea. We call them 'oviparous' sharks and they comprise mainly the small shysharks and skates. Unlike birds, they don’t care for their young.

Inside the egg is a shark embryo with a large yolk sac which it feeds off while growing. Often there are tendrils or hooks on the egg case which secures the egg onto a plant or rock. When the yolk is used up by the growing embryo and the embryo is ready, it hatches from the egg case, which then often washes out onto the beach.

The most commonly found egg cases on Grotto are those of the St Joseph shark, also known as a Cape ghost shark or Cape elephantfish (Callorhinchus capensis). Other types of shark eggs commonly found are puffadder shyshark, dark shyshark and spearnose skate.

Click below to read more. (The full article can be found on page 20)